/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view.textclassifier;

import static java.time.temporal.ChronoUnit.MILLIS;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.WorkerThread;
import android.app.PendingIntent;
import android.app.RemoteAction;
import android.app.SearchManager;
import android.content.ComponentName;
import android.content.ContentUris;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.graphics.drawable.Icon;
import android.net.Uri;
import android.os.Bundle;
import android.os.LocaleList;
import android.os.ParcelFileDescriptor;
import android.os.UserManager;
import android.provider.Browser;
import android.provider.CalendarContract;
import android.provider.ContactsContract;

import com.android.internal.annotations.GuardedBy;
import com.android.internal.util.Preconditions;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.time.Instant;
import java.time.ZonedDateTime;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.StringJoiner;
import java.util.concurrent.TimeUnit;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

Default implementation of the TextClassifier interface. 
This class uses machine learning to recognize entities in text.
Unless otherwise stated, methods of this class are blocking operations and should most
likely not be called on the UI thread.
@hide
/**
 * Default implementation of the {@link TextClassifier} interface.
 *
 * <p>This class uses machine learning to recognize entities in text.
 * Unless otherwise stated, methods of this class are blocking operations and should most
 * likely not be called on the UI thread.
 *
 * @hide
 */
public final class TextClassifierImpl implements TextClassifier {

    private static final String LOG_TAG = DEFAULT_LOG_TAG;
    private static final String MODEL_DIR = "/etc/textclassifier/";
    private static final String MODEL_FILE_REGEX = "textclassifier\\.(.*)\\.model";
    private static final String UPDATED_MODEL_FILE_PATH =
            "/data/misc/textclassifier/textclassifier.model";

    private final Context mContext;
    private final TextClassifier mFallback;
    private final GenerateLinksLogger mGenerateLinksLogger;

    private final Object mLock = new Object();
    @GuardedBy("mLock") // Do not access outside this lock.
    private List<ModelFile> mAllModelFiles;
    @GuardedBy("mLock") // Do not access outside this lock.
    private ModelFile mModel;
    @GuardedBy("mLock") // Do not access outside this lock.
    private TextClassifierImplNative mNative;

    private final Object mLoggerLock = new Object();
    @GuardedBy("mLoggerLock") // Do not access outside this lock.
    private SelectionSessionLogger mSessionLogger;

    private final TextClassificationConstants mSettings;

    public TextClassifierImpl(
            Context context, TextClassificationConstants settings, TextClassifier fallback) {
        mContext = Preconditions.checkNotNull(context);
        mFallback = Preconditions.checkNotNull(fallback);
        mSettings = Preconditions.checkNotNull(settings);
        mGenerateLinksLogger = new GenerateLinksLogger(mSettings.getGenerateLinksLogSampleRate());
    }

    public TextClassifierImpl(Context context, TextClassificationConstants settings) {
        this(context, settings, TextClassifier.NO_OP);
    }

    
@inheritDoc
/** @inheritDoc */
    @Override
    @WorkerThread
    public TextSelection suggestSelection(TextSelection.Request request) {
        Preconditions.checkNotNull(request);
        Utils.checkMainThread();
        try {
            final int rangeLength = request.getEndIndex() - request.getStartIndex();
            final String string = request.getText().toString();
            if (string.length() > 0
                    && rangeLength <= mSettings.getSuggestSelectionMaxRangeLength()) {
                final String localesString = concatenateLocales(request.getDefaultLocales());
                final ZonedDateTime refTime = ZonedDateTime.now();
                final TextClassifierImplNative nativeImpl = getNative(request.getDefaultLocales());
                final int start;
                final int end;
                if (mSettings.isModelDarkLaunchEnabled() && !request.isDarkLaunchAllowed()) {
                    start = request.getStartIndex();
                    end = request.getEndIndex();
                } else {
                    final int[] startEnd = nativeImpl.suggestSelection(
                            string, request.getStartIndex(), request.getEndIndex(),
                            new TextClassifierImplNative.SelectionOptions(localesString));
                    start = startEnd[0];
                    end = startEnd[1];
                }
                if (start < end
                        && start >= 0 && end <= string.length()
                        && start <= request.getStartIndex() && end >= request.getEndIndex()) {
                    final TextSelection.Builder tsBuilder = new TextSelection.Builder(start, end);
                    final TextClassifierImplNative.ClassificationResult[] results =
                            nativeImpl.classifyText(
                                    string, start, end,
                                    new TextClassifierImplNative.ClassificationOptions(
                                            refTime.toInstant().toEpochMilli(),
                                            refTime.getZone().getId(),
                                            localesString));
                    final int size = results.length;
                    for (int i = 0; i < size; i++) {
                        tsBuilder.setEntityType(results[i].getCollection(), results[i].getScore());
                    }
                    return tsBuilder.setId(createId(
                            string, request.getStartIndex(), request.getEndIndex()))
                            .build();
                } else {
                    // We can not trust the result. Log the issue and ignore the result.
                    Log.d(LOG_TAG, "Got bad indices for input text. Ignoring result.");
                }
            }
        } catch (Throwable t) {
            // Avoid throwing from this method. Log the error.
            Log.e(LOG_TAG,
                    "Error suggesting selection for text. No changes to selection suggested.",
                    t);
        }
        // Getting here means something went wrong, return a NO_OP result.
        return mFallback.suggestSelection(request);
    }

    
@inheritDoc
/** @inheritDoc */
    @Override
    @WorkerThread
    public TextClassification classifyText(TextClassification.Request request) {
        Preconditions.checkNotNull(request);
        Utils.checkMainThread();
        try {
            final int rangeLength = request.getEndIndex() - request.getStartIndex();
            final String string = request.getText().toString();
            if (string.length() > 0 && rangeLength <= mSettings.getClassifyTextMaxRangeLength()) {
                final String localesString = concatenateLocales(request.getDefaultLocales());
                final ZonedDateTime refTime = request.getReferenceTime() != null
                        ? request.getReferenceTime() : ZonedDateTime.now();
                final TextClassifierImplNative.ClassificationResult[] results =
                        getNative(request.getDefaultLocales())
                                .classifyText(
                                        string, request.getStartIndex(), request.getEndIndex(),
                                        new TextClassifierImplNative.ClassificationOptions(
                                                refTime.toInstant().toEpochMilli(),
                                                refTime.getZone().getId(),
                                                localesString));
                if (results.length > 0) {
                    return createClassificationResult(
                            results, string,
                            request.getStartIndex(), request.getEndIndex(), refTime.toInstant());
                }
            }
        } catch (Throwable t) {
            // Avoid throwing from this method. Log the error.
            Log.e(LOG_TAG, "Error getting text classification info.", t);
        }
        // Getting here means something went wrong, return a NO_OP result.
        return mFallback.classifyText(request);
    }

    
@inheritDoc
/** @inheritDoc */
    @Override
    @WorkerThread
    public TextLinks generateLinks(@NonNull TextLinks.Request request) {
        Preconditions.checkNotNull(request);
        Utils.checkTextLength(request.getText(), getMaxGenerateLinksTextLength());
        Utils.checkMainThread();

        if (!mSettings.isSmartLinkifyEnabled() && request.isLegacyFallback()) {
            return Utils.generateLegacyLinks(request);
        }

        final String textString = request.getText().toString();
        final TextLinks.Builder builder = new TextLinks.Builder(textString);

        try {
            final long startTimeMs = System.currentTimeMillis();
            final ZonedDateTime refTime = ZonedDateTime.now();
            final Collection<String> entitiesToIdentify = request.getEntityConfig() != null
                    ? request.getEntityConfig().resolveEntityListModifications(
                            getEntitiesForHints(request.getEntityConfig().getHints()))
                    : mSettings.getEntityListDefault();
            final TextClassifierImplNative nativeImpl =
                    getNative(request.getDefaultLocales());
            final TextClassifierImplNative.AnnotatedSpan[] annotations =
                    nativeImpl.annotate(
                        textString,
                        new TextClassifierImplNative.AnnotationOptions(
                                refTime.toInstant().toEpochMilli(),
                                        refTime.getZone().getId(),
                                concatenateLocales(request.getDefaultLocales())));
            for (TextClassifierImplNative.AnnotatedSpan span : annotations) {
                final TextClassifierImplNative.ClassificationResult[] results =
                        span.getClassification();
                if (results.length == 0
                        || !entitiesToIdentify.contains(results[0].getCollection())) {
                    continue;
                }
                final Map<String, Float> entityScores = new HashMap<>();
                for (int i = 0; i < results.length; i++) {
                    entityScores.put(results[i].getCollection(), results[i].getScore());
                }
                builder.addLink(span.getStartIndex(), span.getEndIndex(), entityScores);
            }
            final TextLinks links = builder.build();
            final long endTimeMs = System.currentTimeMillis();
            final String callingPackageName = request.getCallingPackageName() == null
                    ? mContext.getPackageName()  // local (in process) TC.
                    : request.getCallingPackageName();
            mGenerateLinksLogger.logGenerateLinks(
                    request.getText(), links, callingPackageName, endTimeMs - startTimeMs);
            return links;
        } catch (Throwable t) {
            // Avoid throwing from this method. Log the error.
            Log.e(LOG_TAG, "Error getting links info.", t);
        }
        return mFallback.generateLinks(request);
    }

    
@inheritDoc
/** @inheritDoc */
    @Override
    public int getMaxGenerateLinksTextLength() {
        return mSettings.getGenerateLinksMaxTextLength();
    }

    private Collection<String> getEntitiesForHints(Collection<String> hints) {
        final boolean editable = hints.contains(HINT_TEXT_IS_EDITABLE);
        final boolean notEditable = hints.contains(HINT_TEXT_IS_NOT_EDITABLE);

        // Use the default if there is no hint, or conflicting ones.
        final boolean useDefault = editable == notEditable;
        if (useDefault) {
            return mSettings.getEntityListDefault();
        } else if (editable) {
            return mSettings.getEntityListEditable();
        } else {  // notEditable
            return mSettings.getEntityListNotEditable();
        }
    }

    @Override
    public void onSelectionEvent(SelectionEvent event) {
        Preconditions.checkNotNull(event);
        synchronized (mLoggerLock) {
            if (mSessionLogger == null) {
                mSessionLogger = new SelectionSessionLogger();
            }
            mSessionLogger.writeEvent(event);
        }
    }

    private TextClassifierImplNative getNative(LocaleList localeList)
            throws FileNotFoundException {
        synchronized (mLock) {
            localeList = localeList == null ? LocaleList.getEmptyLocaleList() : localeList;
            final ModelFile bestModel = findBestModelLocked(localeList);
            if (bestModel == null) {
                throw new FileNotFoundException("No model for " + localeList.toLanguageTags());
            }
            if (mNative == null || !Objects.equals(mModel, bestModel)) {
                Log.d(DEFAULT_LOG_TAG, "Loading " + bestModel);
                destroyNativeIfExistsLocked();
                final ParcelFileDescriptor fd = ParcelFileDescriptor.open(
                        new File(bestModel.getPath()), ParcelFileDescriptor.MODE_READ_ONLY);
                mNative = new TextClassifierImplNative(fd.getFd());
                closeAndLogError(fd);
                mModel = bestModel;
            }
            return mNative;
        }
    }

    private String createId(String text, int start, int end) {
        synchronized (mLock) {
            return SelectionSessionLogger.createId(text, start, end, mContext, mModel.getVersion(),
                    mModel.getSupportedLocales());
        }
    }

    @GuardedBy("mLock") // Do not call outside this lock.
    private void destroyNativeIfExistsLocked() {
        if (mNative != null) {
            mNative.close();
            mNative = null;
        }
    }

    private static String concatenateLocales(@Nullable LocaleList locales) {
        return (locales == null) ? "" : locales.toLanguageTags();
    }

    
Finds the most appropriate model to use for the given target locale list.
The basic logic is: we ignore all models that don't support any of the target locales. For
the remaining candidates, we take the update model unless its version number is lower than
the factory version. It's assumed that factory models do not have overlapping locale ranges
and conflict resolution between these models hence doesn't matter.
/**
     * Finds the most appropriate model to use for the given target locale list.
     *
     * The basic logic is: we ignore all models that don't support any of the target locales. For
     * the remaining candidates, we take the update model unless its version number is lower than
     * the factory version. It's assumed that factory models do not have overlapping locale ranges
     * and conflict resolution between these models hence doesn't matter.
     */
    @GuardedBy("mLock") // Do not call outside this lock.
    @Nullable
    private ModelFile findBestModelLocked(LocaleList localeList) {
        // Specified localeList takes priority over the system default, so it is listed first.
        final String languages = localeList.isEmpty()
                ? LocaleList.getDefault().toLanguageTags()
                : localeList.toLanguageTags() + "," + LocaleList.getDefault().toLanguageTags();
        final List<Locale.LanguageRange> languageRangeList = Locale.LanguageRange.parse(languages);

        ModelFile bestModel = null;
        for (ModelFile model : listAllModelsLocked()) {
            if (model.isAnyLanguageSupported(languageRangeList)) {
                if (model.isPreferredTo(bestModel)) {
                    bestModel = model;
                }
            }
        }
        return bestModel;
    }

    
Returns a list of all model files available, in order of precedence. /** Returns a list of all model files available, in order of precedence. */
    @GuardedBy("mLock") // Do not call outside this lock.
    private List<ModelFile> listAllModelsLocked() {
        if (mAllModelFiles == null) {
            final List<ModelFile> allModels = new ArrayList<>();
            // The update model has the highest precedence.
            if (new File(UPDATED_MODEL_FILE_PATH).exists()) {
                final ModelFile updatedModel = ModelFile.fromPath(UPDATED_MODEL_FILE_PATH);
                if (updatedModel != null) {
                    allModels.add(updatedModel);
                }
            }
            // Factory models should never have overlapping locales, so the order doesn't matter.
            final File modelsDir = new File(MODEL_DIR);
            if (modelsDir.exists() && modelsDir.isDirectory()) {
                final File[] modelFiles = modelsDir.listFiles();
                final Pattern modelFilenamePattern = Pattern.compile(MODEL_FILE_REGEX);
                for (File modelFile : modelFiles) {
                    final Matcher matcher = modelFilenamePattern.matcher(modelFile.getName());
                    if (matcher.matches() && modelFile.isFile()) {
                        final ModelFile model = ModelFile.fromPath(modelFile.getAbsolutePath());
                        if (model != null) {
                            allModels.add(model);
                        }
                    }
                }
            }
            mAllModelFiles = allModels;
        }
        return mAllModelFiles;
    }

    private TextClassification createClassificationResult(
            TextClassifierImplNative.ClassificationResult[] classifications,
            String text, int start, int end, @Nullable Instant referenceTime) {
        final String classifiedText = text.substring(start, end);
        final TextClassification.Builder builder = new TextClassification.Builder()
                .setText(classifiedText);

        final int size = classifications.length;
        TextClassifierImplNative.ClassificationResult highestScoringResult = null;
        float highestScore = Float.MIN_VALUE;
        for (int i = 0; i < size; i++) {
            builder.setEntityType(classifications[i].getCollection(),
                                  classifications[i].getScore());
            if (classifications[i].getScore() > highestScore) {
                highestScoringResult = classifications[i];
                highestScore = classifications[i].getScore();
            }
        }

        boolean isPrimaryAction = true;
        for (LabeledIntent labeledIntent : IntentFactory.create(
                mContext, referenceTime, highestScoringResult, classifiedText)) {
            final RemoteAction action = labeledIntent.asRemoteAction(mContext);
            if (action == null) {
                continue;
            }
            if (isPrimaryAction) {
                // For O backwards compatibility, the first RemoteAction is also written to the
                // legacy API fields.
                builder.setIcon(action.getIcon().loadDrawable(mContext));
                builder.setLabel(action.getTitle().toString());
                builder.setIntent(labeledIntent.getIntent());
                builder.setOnClickListener(TextClassification.createIntentOnClickListener(
                        TextClassification.createPendingIntent(mContext,
                                labeledIntent.getIntent(), labeledIntent.getRequestCode())));
                isPrimaryAction = false;
            }
            builder.addAction(action);
        }

        return builder.setId(createId(text, start, end)).build();
    }

    
Closes the ParcelFileDescriptor and logs any errors that occur.
/**
     * Closes the ParcelFileDescriptor and logs any errors that occur.
     */
    private static void closeAndLogError(ParcelFileDescriptor fd) {
        try {
            fd.close();
        } catch (IOException e) {
            Log.e(LOG_TAG, "Error closing file.", e);
        }
    }

    
Describes TextClassifier model files on disk.
/**
     * Describes TextClassifier model files on disk.
     */
    private static final class ModelFile {

        private final String mPath;
        private final String mName;
        private final int mVersion;
        private final List<Locale> mSupportedLocales;
        private final boolean mLanguageIndependent;

        
Returns null if the path did not point to a compatible model. /** Returns null if the path did not point to a compatible model. */
        static @Nullable ModelFile fromPath(String path) {
            final File file = new File(path);
            try {
                final ParcelFileDescriptor modelFd = ParcelFileDescriptor.open(
                        file, ParcelFileDescriptor.MODE_READ_ONLY);
                final int version = TextClassifierImplNative.getVersion(modelFd.getFd());
                final String supportedLocalesStr =
                        TextClassifierImplNative.getLocales(modelFd.getFd());
                if (supportedLocalesStr.isEmpty()) {
                    Log.d(DEFAULT_LOG_TAG, "Ignoring " + file.getAbsolutePath());
                    return null;
                }
                final boolean languageIndependent = supportedLocalesStr.equals("*");
                final List<Locale> supportedLocales = new ArrayList<>();
                for (String langTag : supportedLocalesStr.split(",")) {
                    supportedLocales.add(Locale.forLanguageTag(langTag));
                }
                closeAndLogError(modelFd);
                return new ModelFile(path, file.getName(), version, supportedLocales,
                                     languageIndependent);
            } catch (FileNotFoundException e) {
                Log.e(DEFAULT_LOG_TAG, "Failed to peek " + file.getAbsolutePath(), e);
                return null;
            }
        }

        
The absolute path to the model file. /** The absolute path to the model file. */
        String getPath() {
            return mPath;
        }

        
A name to use for id generation. Effectively the name of the model file. /** A name to use for id generation. Effectively the name of the model file. */
        String getName() {
            return mName;
        }

        
Returns the version tag in the model's metadata. /** Returns the version tag in the model's metadata. */
        int getVersion() {
            return mVersion;
        }

        
Returns whether the language supports any language in the given ranges. /** Returns whether the language supports any language in the given ranges. */
        boolean isAnyLanguageSupported(List<Locale.LanguageRange> languageRanges) {
            return mLanguageIndependent || Locale.lookup(languageRanges, mSupportedLocales) != null;
        }

        
All locales supported by the model. /** All locales supported by the model. */
        List<Locale> getSupportedLocales() {
            return Collections.unmodifiableList(mSupportedLocales);
        }

        public boolean isPreferredTo(ModelFile model) {
            // A model is preferred to no model.
            if (model == null) {
                return true;
            }

            // A language-specific model is preferred to a language independent
            // model.
            if (!mLanguageIndependent && model.mLanguageIndependent) {
                return true;
            }

            // A higher-version model is preferred.
            if (getVersion() > model.getVersion()) {
                return true;
            }
            return false;
        }

        @Override
        public boolean equals(Object other) {
            if (this == other) {
                return true;
            } else if (other == null || !ModelFile.class.isAssignableFrom(other.getClass())) {
                return false;
            } else {
                final ModelFile otherModel = (ModelFile) other;
                return mPath.equals(otherModel.mPath);
            }
        }

        @Override
        public String toString() {
            final StringJoiner localesJoiner = new StringJoiner(",");
            for (Locale locale : mSupportedLocales) {
                localesJoiner.add(locale.toLanguageTag());
            }
            return String.format(Locale.US, "ModelFile { path=%s name=%s version=%d locales=%s }",
                    mPath, mName, mVersion, localesJoiner.toString());
        }

        private ModelFile(String path, String name, int version, List<Locale> supportedLocales,
                          boolean languageIndependent) {
            mPath = path;
            mName = name;
            mVersion = version;
            mSupportedLocales = supportedLocales;
            mLanguageIndependent = languageIndependent;
        }
    }

    
Helper class to store the information from which RemoteActions are built.
/**
     * Helper class to store the information from which RemoteActions are built.
     */
    private static final class LabeledIntent {

        static final int DEFAULT_REQUEST_CODE = 0;

        private final String mTitle;
        private final String mDescription;
        private final Intent mIntent;
        private final int mRequestCode;

        
Initializes a LabeledIntent.
NOTE: reqestCode is required to not be DEFAULT_REQUEST_CODE if distinguishing info (e.g. the classified text) is represented in intent extras only. In such circumstances, the request code should represent the distinguishing info (e.g. by generating a hashcode) so that the generated PendingIntent is (somewhat) unique. To be correct, the PendingIntent should be definitely unique but we try a best effort approach that avoids spamming the system with PendingIntents. /**
         * Initializes a LabeledIntent.
         *
         * <p>NOTE: {@code reqestCode} is required to not be {@link #DEFAULT_REQUEST_CODE}
         * if distinguishing info (e.g. the classified text) is represented in intent extras only.
         * In such circumstances, the request code should represent the distinguishing info
         * (e.g. by generating a hashcode) so that the generated PendingIntent is (somewhat)
         * unique. To be correct, the PendingIntent should be definitely unique but we try a
         * best effort approach that avoids spamming the system with PendingIntents.
         */
        // TODO: Fix the issue mentioned above so the behaviour is correct.
        LabeledIntent(String title, String description, Intent intent, int requestCode) {
            mTitle = title;
            mDescription = description;
            mIntent = intent;
            mRequestCode = requestCode;
        }

        String getTitle() {
            return mTitle;
        }

        String getDescription() {
            return mDescription;
        }

        Intent getIntent() {
            return mIntent;
        }

        int getRequestCode() {
            return mRequestCode;
        }

        @Nullable
        RemoteAction asRemoteAction(Context context) {
            final PackageManager pm = context.getPackageManager();
            final ResolveInfo resolveInfo = pm.resolveActivity(mIntent, 0);
            final String packageName = resolveInfo != null && resolveInfo.activityInfo != null
                    ? resolveInfo.activityInfo.packageName : null;
            Icon icon = null;
            boolean shouldShowIcon = false;
            if (packageName != null && !"android".equals(packageName)) {
                // There is a default activity handling the intent.
                mIntent.setComponent(new ComponentName(packageName, resolveInfo.activityInfo.name));
                if (resolveInfo.activityInfo.getIconResource() != 0) {
                    icon = Icon.createWithResource(
                            packageName, resolveInfo.activityInfo.getIconResource());
                    shouldShowIcon = true;
                }
            }
            if (icon == null) {
                // RemoteAction requires that there be an icon.
                icon = Icon.createWithResource("android",
                        com.android.internal.R.drawable.ic_more_items);
            }
            final PendingIntent pendingIntent =
                    TextClassification.createPendingIntent(context, mIntent, mRequestCode);
            if (pendingIntent == null) {
                return null;
            }
            final RemoteAction action = new RemoteAction(icon, mTitle, mDescription, pendingIntent);
            action.setShouldShowIcon(shouldShowIcon);
            return action;
        }
    }

    
Creates intents based on the classification type.
/**
     * Creates intents based on the classification type.
     */
    static final class IntentFactory {

        private static final long MIN_EVENT_FUTURE_MILLIS = TimeUnit.MINUTES.toMillis(5);
        private static final long DEFAULT_EVENT_DURATION = TimeUnit.HOURS.toMillis(1);

        private IntentFactory() {}

        @NonNull
        public static List<LabeledIntent> create(
                Context context,
                @Nullable Instant referenceTime,
                TextClassifierImplNative.ClassificationResult classification,
                String text) {
            final String type = classification.getCollection().trim().toLowerCase(Locale.ENGLISH);
            text = text.trim();
            switch (type) {
                case TextClassifier.TYPE_EMAIL:
                    return createForEmail(context, text);
                case TextClassifier.TYPE_PHONE:
                    return createForPhone(context, text);
                case TextClassifier.TYPE_ADDRESS:
                    return createForAddress(context, text);
                case TextClassifier.TYPE_URL:
                    return createForUrl(context, text);
                case TextClassifier.TYPE_DATE:
                case TextClassifier.TYPE_DATE_TIME:
                    if (classification.getDatetimeResult() != null) {
                        final Instant parsedTime = Instant.ofEpochMilli(
                                classification.getDatetimeResult().getTimeMsUtc());
                        return createForDatetime(context, type, referenceTime, parsedTime);
                    } else {
                        return new ArrayList<>();
                    }
                case TextClassifier.TYPE_FLIGHT_NUMBER:
                    return createForFlight(context, text);
                default:
                    return new ArrayList<>();
            }
        }

        @NonNull
        private static List<LabeledIntent> createForEmail(Context context, String text) {
            return Arrays.asList(
                    new LabeledIntent(
                            context.getString(com.android.internal.R.string.email),
                            context.getString(com.android.internal.R.string.email_desc),
                            new Intent(Intent.ACTION_SENDTO)
                                    .setData(Uri.parse(String.format("mailto:%s", text))),
                            LabeledIntent.DEFAULT_REQUEST_CODE),
                    new LabeledIntent(
                            context.getString(com.android.internal.R.string.add_contact),
                            context.getString(com.android.internal.R.string.add_contact_desc),
                            new Intent(Intent.ACTION_INSERT_OR_EDIT)
                                    .setType(ContactsContract.Contacts.CONTENT_ITEM_TYPE)
                                    .putExtra(ContactsContract.Intents.Insert.EMAIL, text),
                            text.hashCode()));
        }

        @NonNull
        private static List<LabeledIntent> createForPhone(Context context, String text) {
            final List<LabeledIntent> actions = new ArrayList<>();
            final UserManager userManager = context.getSystemService(UserManager.class);
            final Bundle userRestrictions = userManager != null
                    ? userManager.getUserRestrictions() : new Bundle();
            if (!userRestrictions.getBoolean(UserManager.DISALLOW_OUTGOING_CALLS, false)) {
                actions.add(new LabeledIntent(
                        context.getString(com.android.internal.R.string.dial),
                        context.getString(com.android.internal.R.string.dial_desc),
                        new Intent(Intent.ACTION_DIAL).setData(
                                Uri.parse(String.format("tel:%s", text))),
                        LabeledIntent.DEFAULT_REQUEST_CODE));
            }
            actions.add(new LabeledIntent(
                    context.getString(com.android.internal.R.string.add_contact),
                    context.getString(com.android.internal.R.string.add_contact_desc),
                    new Intent(Intent.ACTION_INSERT_OR_EDIT)
                            .setType(ContactsContract.Contacts.CONTENT_ITEM_TYPE)
                            .putExtra(ContactsContract.Intents.Insert.PHONE, text),
                    text.hashCode()));
            if (!userRestrictions.getBoolean(UserManager.DISALLOW_SMS, false)) {
                actions.add(new LabeledIntent(
                        context.getString(com.android.internal.R.string.sms),
                        context.getString(com.android.internal.R.string.sms_desc),
                        new Intent(Intent.ACTION_SENDTO)
                                .setData(Uri.parse(String.format("smsto:%s", text))),
                        LabeledIntent.DEFAULT_REQUEST_CODE));
            }
            return actions;
        }

        @NonNull
        private static List<LabeledIntent> createForAddress(Context context, String text) {
            final List<LabeledIntent> actions = new ArrayList<>();
            try {
                final String encText = URLEncoder.encode(text, "UTF-8");
                actions.add(new LabeledIntent(
                        context.getString(com.android.internal.R.string.map),
                        context.getString(com.android.internal.R.string.map_desc),
                        new Intent(Intent.ACTION_VIEW)
                                .setData(Uri.parse(String.format("geo:0,0?q=%s", encText))),
                        LabeledIntent.DEFAULT_REQUEST_CODE));
            } catch (UnsupportedEncodingException e) {
                Log.e(LOG_TAG, "Could not encode address", e);
            }
            return actions;
        }

        @NonNull
        private static List<LabeledIntent> createForUrl(Context context, String text) {
            if (Uri.parse(text).getScheme() == null) {
                text = "http://" + text;
            }
            return Arrays.asList(new LabeledIntent(
                    context.getString(com.android.internal.R.string.browse),
                    context.getString(com.android.internal.R.string.browse_desc),
                    new Intent(Intent.ACTION_VIEW, Uri.parse(text))
                            .putExtra(Browser.EXTRA_APPLICATION_ID, context.getPackageName()),
                    LabeledIntent.DEFAULT_REQUEST_CODE));
        }

        @NonNull
        private static List<LabeledIntent> createForDatetime(
                Context context, String type, @Nullable Instant referenceTime,
                Instant parsedTime) {
            if (referenceTime == null) {
                // If no reference time was given, use now.
                referenceTime = Instant.now();
            }
            List<LabeledIntent> actions = new ArrayList<>();
            actions.add(createCalendarViewIntent(context, parsedTime));
            final long millisUntilEvent = referenceTime.until(parsedTime, MILLIS);
            if (millisUntilEvent > MIN_EVENT_FUTURE_MILLIS) {
                actions.add(createCalendarCreateEventIntent(context, parsedTime, type));
            }
            return actions;
        }

        @NonNull
        private static List<LabeledIntent> createForFlight(Context context, String text) {
            return Arrays.asList(new LabeledIntent(
                    context.getString(com.android.internal.R.string.view_flight),
                    context.getString(com.android.internal.R.string.view_flight_desc),
                    new Intent(Intent.ACTION_WEB_SEARCH)
                            .putExtra(SearchManager.QUERY, text),
                    text.hashCode()));
        }

        @NonNull
        private static LabeledIntent createCalendarViewIntent(Context context, Instant parsedTime) {
            Uri.Builder builder = CalendarContract.CONTENT_URI.buildUpon();
            builder.appendPath("time");
            ContentUris.appendId(builder, parsedTime.toEpochMilli());
            return new LabeledIntent(
                    context.getString(com.android.internal.R.string.view_calendar),
                    context.getString(com.android.internal.R.string.view_calendar_desc),
                    new Intent(Intent.ACTION_VIEW).setData(builder.build()),
                    LabeledIntent.DEFAULT_REQUEST_CODE);
        }

        @NonNull
        private static LabeledIntent createCalendarCreateEventIntent(
                Context context, Instant parsedTime, @EntityType String type) {
            final boolean isAllDay = TextClassifier.TYPE_DATE.equals(type);
            return new LabeledIntent(
                    context.getString(com.android.internal.R.string.add_calendar_event),
                    context.getString(com.android.internal.R.string.add_calendar_event_desc),
                    new Intent(Intent.ACTION_INSERT)
                            .setData(CalendarContract.Events.CONTENT_URI)
                            .putExtra(CalendarContract.EXTRA_EVENT_ALL_DAY, isAllDay)
                            .putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME,
                                    parsedTime.toEpochMilli())
                            .putExtra(CalendarContract.EXTRA_EVENT_END_TIME,
                                    parsedTime.toEpochMilli() + DEFAULT_EVENT_DURATION),
                    parsedTime.hashCode());
        }
    }
}